package 链表;

/**
 * https://leetcode-cn.com/problems/linked-list-cycle/
 *
 */
public class _141_环形链表 {
	 public boolean hasCycle(ListNode head) {
		 if(head == null || head.next == null) return false;
		 ListNode slow = head;
		 ListNode fast = head.next;
		 while(fast != null && fast.next != null) {
			slow = slow.next;
			fast = fast.next.next;
			if(slow == fast) {
				return true;
			}
		 }
		 return false;
	 }
}
